Method of and apparatus for saturating sheet material by calenders



June 10, 1930. w, G, DUDLESTON 1,762,329

METHOD OF AND APPARATUS FOR SATURATING SHEET MATERIAL BY CALENDERS FiledJuhe 11. 1926 `atented ,lune W, w3@

WILLIAM G. DUDLESTON, OF CHICAGO HEIGHTS, ILLINOIS, ASSIGNOR, BY MESNEAS- SIGNMENTS, TO THE PATENT AND LICENSING CORIPORATION,- OF lBOSTON,MAS- y SACHUSETTS, A CORPORATION OF MASSACHUSETTS METHOD OF ANDAPPARATUS FOR SATUBATING SHEET MATERIAL BY GALENDERS Application medJune 1i,

This invention relates to a method of and apparatus for -saturatingsheet material, and is more particularly designed for the continuousprogressive saturation of a web of ,a indeterminate length, being alsoespecially suitable for webs of comparatively slight tensile strength.

Apparatus embodying my invention finds a field of utility in themanufactured roofing art. A large amount of the manufactured roofing oftoday is Vmade of sheets of feltedv fibrous material which are saturatedand coated with asphaltic compounds, and further treated in variousways. The material commonly used as a base for such roong is made from apulp of rag or asbestos fibers, or the, like, which is formed intocontinuous sheets in a paper-making machine, the fibers being looselyfelted to- .20 gether as the sheet is formed. Sheet material of thiskind, known as roofing felt, is ordinarily of a relatively loose,(porous texture, capable of absorbing a consi erable quantity ofsaturant. It has, however, relatively low tensile strength so that theproblem of feeding such material without subjecting it to morethan'moderate tensile stresses is one which demands consideration in theconstruction of a machine to handle and operate upon it. This isparticularly true of the'step of saturating with a lique fled asphalticcompound. The liquid asphalt is of an oily consistency, and has atendency to lubricate the interfelted fibers,l

ythus reducing vfurther the tensile strength ofthe sheet. ln order tofill up the pores and voids betweenthe fibers in the sheet by immersingthe sheetin a pool of saturant, the saturant must have a relatively highdegree of fluidity, preferably combined with alternating changes ofpressure to Vallow the air orl gases caught in the pores to escape andto force the saturant thereinto. Where commonly used asphaltic compoundsare employed as saturants, the fluidity is usually obtained byh'eatwhile the pressure changes may be effected by leading the sheet down andup a number of times in a deep body of saturant, the head of the liquidproducing 50 the increased pressure.

1926.l Serial No. 115,89.

In order to obtain suihcient fluidity of the saturant without raising itto a prohibitive temperature which would tend to scorch or injure thefibrous sheet, it is necessary to vuse a relatively low melting-pointasphalt practice, the sheet is led through a pool of low melting-pointasphalt of considerable size inorder to provide suciently extensiveimmersion for thorough saturation. The Immersion step may be carried outby leading the web beneath the surface of the saturant at one end of acontainer of considerable length, extending it through the saturant forsubstantially the entirelength of the container, and leading it out atthe further end. Or series of upper and lower rolls may be providedin acontainer of considerable depth, the web being passed over the upper andlower rolls alternately. In either case, a considerable length of web isdrawn through the body of thesaturant again'stthe skin friction of thesaturant on the rough fibrous 'faces of the web. This dragging actioncombined with the `weakening effect of the saturant upon the fibrousstructure of the web renders the latter linable to breakage,particularly if for p any reason the viscosity of the saturant happensto increase. As a result, it is'necessary to keep a relatively largebody of saturant at a given temperature and it is also necessary to'devote a considerable amount of fioor space in a plant forthesaturating pool.

`The tops of these pools are frequently flush or nearly flush withthefloor level, a source of danger to the workmen attending theapparatus.

By my invention, I provide apparatus which occupies relatively littleoor space, which enables felted sheet material to be fed through thesaturating process with very littletension on the sheet and hencepractically no danger of breakage of the sheet,

the sheet firmly therebetween, liquid saturant being flowed upon a faceof the sheet immediately prior to its passage between eaclrpair of therolls, so that the saturant is rolled together with the web and ispressed thereinto and therethrough. This held in the voids between thefibers.

step of squeezing and pressing the felt sheet and the saturant iseffective only to the extent of thoroughly coating or wetting theindividual fibers in the sheet. Further squeezing of thesheet'preventsthe further absorption of saturant; in fact, once thelfibers are wetted, squeezing the sheet tends to press-saturant out ofthe sheet, after the manner of a wringer pressing from a wet towel waterthat has been taken up arIid n order to complete the saturation of thesheet therefore, it is necessary to follow the squeezing process byfurther treatment to l fill up the voids or pores in the sheet. ThisAmay be accomplished .by pressing saturant against a face `of the sheetwithout squeezing the sheet. This may be done by passing the sheetthrough a stack of rolls whichare supported with sufficient clearance topermit the passage of the sheet vand a layer of saturant. By fiowing thesaturant on the sheet as it comes into contact with each roll, theliquid is caught between the sheet and roll and is pressed into the oresof the felt without any squeezing o the sheet itself.

The saturating action of the rolls can bemade more effective by suitabletemperature control.V If the temperature of the sheet, after beingthoroughly wetted with saturant, is progressively reduced in thevpresence of excess saturant, the contraction of the vsaturant andresidual air in the sheet occasioned by the cooling, draws more of thesaturant into the sheet. This feature of temperature control maybecarried out by regulating the steam admitted to successive rolls in astack so that each successive roll in the stack is coolerl than theonebefore it. Thus for example a sheet Aof roofing felt is passedthrough a calender stack and squeezed between the nips with asphalt at atemperature of about 450o F., wetting all the fibers thoroughly. Next,the sheet is passed through another calender stack with spaced rolls toobviate squeezing the felt. Excess saturant is 4supplied to both facesas required during the passage of the sheet through the stack and thecooling of the sheet by the successively lower temperatures of the rollscontracts the asphalt and air within the pores and sucks more saturantin. This sucking action in conjunction with the pressing of the rollsagainst the sheet effects a high degree of saturation.

Further details of structure and advantageous features will be set forthin the description which follows and are disclosed on the drawing, ofwhich:

Figure 1 is a side elevation of the apparatus including an embodiment ofmy invention, part of the apparatus being diagrammatically shown.

Figure is an end elevation of a set of calenders.

Figure 3 is a fragmentary showing partly in section of a calender,showing the method of supporting and heating the same.

Fi. re 4 is a View of a spout for supplying liquid saturant to thesheet.

Figure 5 is a sectional view showing the 4manner of application ofsaturant through a spout to the'traveling sheet.

Figure 6 shows an alternative means of applying the saturant to thesheet.

Figure 7 shows an alternative heating means for a calender roll.

Referring to the drawing in detail, 10 represents a supply roll of sheetmaterial, such forA example as roofing felt. In order to maintain acontinuous length of vsheet to pass through the machine, a splicingdevice generally indicated at 11 may be supplied to join the ends ofsuccessive rolls together, a looping device indicated at 12 beingsupplied to provide a reserve supply of sheet to feed through theapparatus during the splicing of ends in the splicer 11. The sheet offelt .is preferably preheated as by a series of heated rolls 13 of whichthere may be any desired number, and which may be heated -in any desiredway, as for example by steam pipes connected as shown in Figure 3. Thepreheated sheet may then be led through a calendering mechanismcomprising a plurality of calender rolls 14 which for economy of floorspace and utilization of gravity. pressure may be arranged in superposedrelation. The rolls 14 are each supported on a cross bar 15 at each endof the roll, these cross bars 15 resting on nuts 16 which are adjustablymounted on screw-threaded vertical rods 17 which pass loosely throughperforations in the cross bars 15. 'Ihe nuts 16 are so arranged on therod 17 that when the lat.'- ter are raised by a motor-driven mechanism mIt is pre erred that the rolls 14 be heated to maintain the saturant inHuid conditionand to prevent sticking of the sheet to the rolls. Thismay be done by any desired means suitable .for the required tempera- 15tures, the temperature used being :determined by the characteristics ofthe saturant employed. In the embodiment shown in the drawing meansv forheating the rolls by steam have been indicated in Figures 2 and 3, thepiping beingomitted from Figure4 1 to avoid undue complication ofdetail.As shown in Figure 3,' steam may be introduced through a supply pipe 20,the pipe entering the hollow roll by a suitable packed joint such as iswell known in the steamtitting art. The exhaust pipe 21 may be led inthrough the opposite end 'of the roll, the end 22 being preferablyturned down in order to exhaust from the -bottom lof the roll anycondensed liquid which may be formed there. Valves may be employed onthe branches of the pipes 20 and 21 to regulate the steam supply -to theseveral rolls. Instead offsteam for heating the rolls, I may useelectricity, burning or heated gases, heated oil, or any other heatingagency suitable for the purpose, together with means for regulating thetemperatures of the individual rolls.

As indicated in Figure 1, the saturant is preferably flowed on to asurface of the sheet innnediately before it enters the .nip of a pair ofsuccessive rolls. As the sheet is threaded back andl forth between thesuccessive rolls, saturant is dowed alternately on the two sides of thesheet and from'opposite sides of the stack of rolls. The hot asphalt mayhe suppliedf` through pipes 23 which are 'preferably steam jacketed bysurrounding pipes 24 yin order to maintain the asphalt passingtherethrough at the de`.

sired temperature, and to prevent premature cooling thereof which wouldquickly clog the supply pipes 23. At the delivery end of the supplypipes 23, suitable nozzles 25 are preferably attached, these nozzlesbeing elongated horizontally as indicated in Figure 4f to supply aliquid sheet of saturant to the entire width of the traveling feltsheet. In order to insure thorough saturation, it is preferred to supplyan excess of saturant beyond what the sheet can absorb, the excess beingcaught as by pans 26 and returned by suitable pumping means 2'? t0 theheated reservoir from which the asphalt is supplied to the pipes 23.4

Instead of supplyingthe 'saturant in streams from nozzles 25, I maysubstitute for the nozzles, pansor containers 28 which are supplied withliquid saturant as by pipes 29 and may be maintained atthe propertemperature as by steam pipes 30 or other equivalent heating means. Thepans 28 are constructed with an open end, the sides adjacent that end.being of curved shape to permit the pans to be positioned adjacent tothe rolls with a very'slight clearance be-4 tween the pan and thelsurface of the felt sheet. In this form of construction, the sheet inpassing comes in contact with the body of saturant contained in thepanj28 and picks up a coating of saturant which is carried therewith tothe nip of the rolls.

The layer of saturant deposited upon the sheet either by a nozzle 25orby a pan 28 is worked into the felt as it passes between a pair ofrolls, the pressure of the rolls serv'- ing to squeeze the sheet and topress the porL tion of the saturant into thepores and voidsY thereof, sothat all the individual fibers of the sheet are thoroughly wetted withthe saturant.' If desired, the extent or completeness of saturation maybe controlled to some extent with apparatus of this kind by regulatingthe number of rolls between which the sheet is passed and the pressurebetween successive rolls. The saturant may also be supplied on one sideonly of the stack, it thus being applied successively to one side onlyof the sheet and forced through to the other side. In the drawing twostacks of calendars are illustrated, but as many more may be employed asdesired. For thorough saturation of the sheet it is preferred toseparate the rolls of the second stack so that the sheet will not besqueezed when passing betweenl them. This is easily done by adjustingthe supports for the several rolls. The temperatures of the individualrolls may also be regulated by adjusting the steam valves if steam isused to heat the rolls, or regulating the current if electricit is used.Other heating means may he use if preferred.A It is obvious that eachpair of rolls, besides -pressing the saturant into the felt, will serveas feedrolls to advance the sheet, hence there is 'no considerablelength of the sheet being drawn through a viscous liquid as in the caseof the ordinary saturating tanks, and the liability of damage to thesheet from breaking or tearing is reduced to a minimum. Since a machine.of this kind can be run at a relatively high speed, the sheet passesthrough quickly and is in contact with the heated elements and bodies ofsaturating fluid for only a relai tively short time. Hence it ispossible with this machine to use as a saturantasphaltic compounds ofrelatively high melting-point ico which by reason of their physicalproperties as well as their high melting points, are amore desirableconstituent 4of roofing elements than th(` lower melting-point asphalts.5 Having thus described an embodiment of my invention, it should beevident to those. skilled in the art that many changes and modificationsmay be made therein without departing from its spirit or scope as demfined by the appended claims.

' I claim:

1. The method of saturating a web of fibrous material, which comprisesapplying liquid saturant to the faces of the web, squeezing the web andsaturant together, flowing a film of saturant on each face of the web,and successively pressing said films into the web without squeezing theweb.

'2. The method of saturating a web, of fibrous material with aheat-liquefied saturant,- which comprises applying liquefied saturant tothe web, squeezing the web and saturant together, flowing additionalsaturantonto the faces of the web, and reducing the temperature of theweb and the saturant Carried therewith.

3. The method of saturating a web of fibrous material with aheat-liquefied saturant, which comprises flowing saturant onto 30 thefaces of the web, squeezing the web and saturant together, flowing moresaturant onto the faces ofthe web, pressing alternately against oppositefaces of the web without squeezing the web, and progressively reducingthe temperature of the web during said pressing operations.

4. An apparatus of the class described, comprising a series of rollseach of the intermediate rolls of the series forming a nip 4o with eachof two other rolls and the end rolls forming nips with their respectiveadjacent lntermediate rolls through which nips a web of brous lmaterialmay be fed in zigzag formation, and means for directing streams ofsaturanttowardsaid nips to coat the web as it passes thereto.

5. An apparatus of the class described, Acomprising means for flowingliquid saturant onto the faces of a sheet of fibrous ma# terial, meansfor'squeezing the sheet and the saturant together, said squeezlng meanscomprising a plurality of rolls between 'which the sheet is adapted tobe passed, a series of spaced rolls having suiiicient clearance topermit the passageA of the sheet therebetween without "squeezing, andmeans for iiowing films of saturant onto the faces of the sheetimmediately before contacting the spaced rolls.

In testimony whereof have afiixed my signature.

WILLIAM G. DUDLESTON.

